John Calambokidis stood on the bow of the Salty Lady like an old sea captain, his long white hair and beard blowing in the wind, and pointed out two blue whales surfacing on the starboard side.

A blast of water spouted up from the blowhole of one of the endangered whales as its slick gray back and smallish dorsal fin arched above the waves next to the Oceanic Society boat, which was bobbing in the choppy seas near the Farallon Islands, 27 miles off San Francisco's coast.

"That's about as good a look at blue whales as you're ever going to get," said Calambokidis, the director of the Cascadia Research Collective in Olympia, Wash., and one of the top whale biologists in the world.

Sightings of blue whales, the largest creature to ever live, are rare despite the fact that the biggest concentration in the world feeds along the California coast. Marine biologists are now worried that the giant cetaceans will be driven even closer to extinction by large ships steaming over their feeding grounds.

Calambokidis and other researchers on the recent whale watching expedition said blue whales appear to be more susceptible than other whales to being killed and injured by ships along the California coast, where some of the world's busiest shipping ports exist. More than 3,000 large vessels a year move in and out of San Francisco Bay alone.

Whale populations

Calambokidis' concerns appear to be contradicted by what he said has been a dramatic increase in the overall whale population along the West Coast over the years. Gray and humpback whales are now at or near their historic populations, and the number of fin whales has been increasing. Some 20,000 humpbacks now inhabit the North Pacific.

But blue whales - and a few other whale species - appear not to be faring as well as other cetaceans, and researchers fear ship strikes may be the reason.

Curiously, said Calambokidis, who has studied whales since 1986, it seems that a higher percentage of blue whales than other whales are getting hit by ships.

"With blue whales, I think ship strikes could be a major reason why they haven't recovered from whaling," he said. "There is just so much ship traffic that even a small number of incidents could make a difference."

The most popular shipping route leading to San Francisco Bay skirts the Farallones sanctuary. Just to get there, though, ships must steam over whale feeding grounds along the continental shelf, Calambokidis said.

Experts have proposed, among other things, instituting ship speed limits, assigning whale spotters and making noise to scare off whales, but Calambokidis said the most effective solution would be to reroute the shipping lanes to avoid feeding grounds.

"These are very clustered groups of whales, so you could very easily design shipping lanes to avoid them," said Calambokidis, whose cheeks were red against the biting sea breeze as he stood on the bow and gazed at the two 85-foot whales feeding near the shipping channel. "I think changing shipping lanes is a no- brainer."

Some shipping industry executives and maritime workers are skeptical, however. Capt. Bruce Horton, the president of the San Francisco Bar Pilots, admits that ship strikes occur, but doubts they are as big a problem as some people make them out to be.

"I can only speak to what we see here in San Francisco Bay, and we have not been aware of any increase in whale strikes," Horton said.

Blue whale vulnerability

The abundance in the overall number of whales off the California coast was pretty obvious during the boat ride. At one point, an estimated 20 or 30 humpbacks surrounded the boat, one of which leaped high out of the water and landed with a great splash.

Humpbacks and gray whales are often victims of ship strikes, but Calambokidis said the two species appear from his research to at least try to avoid passing ships. Blue whales were the least likely of any species he tagged and tracked to dive or take other evasive action, he said.

"Initial data showed that blue whales are more often at the surface at night, which would make them more vulnerable to ship strikes," he said. "Also blue whales seem to spend more time on the surface when ships are in the area."

In some cases, Calambokidis said, blue whales were actually documented moving toward large passing vessels. They may have been reacting instinctively to the noise, he said, or they simply did not recognize the danger. In any case, he said, blue whales do not take any noticeable actions to avoid large vessels bearing down upon them.

That is potentially a big problem considering the impact whaling had on the species.

The average adult blue whale, known scientifically as Balaenoptera musculus, is the length of three school buses parked bumper to bumper and weighs up to 100 tons. Its tongue alone is the size of an elephant, and it has a Volkswagen-size heart.

Whalers coveted the giant blubbery beasts, some 200,000 of which once roamed the world's oceans looking for the shrimp-like crustaceans known as krill. Problem was, blue whales were so extraordinarily fast that whaling ships could not even catch them until the 20th century.

The solution came in the form of steam power and high compression harpoons, which allowed whalers to kill vast numbers of blue whales starting in the 1930s until the practice was banned. Fewer than 10,000 now exist in all the oceans.

Deaths studied

Marine biologists took particular note of the shipping issue in 2007, when five dead blue whales washed ashore in Southern California, four of which had major wounds that were found to have been caused by ship strikes.

A 2010 study by some of the top marine mammal experts in California, Oregon and Washington found that eight of the 21 blue whale deaths along the California coast between 1988 and 2007 were a result of ship strikes. The dead whales were all found near shipping lanes entering San Francisco Bay, the Port of Los Angeles, the Port of Long Beach and in the Santa Barbara channel.

Calambokidis said ship strikes account for about a third of all whale strandings.

"You've got to remember that strandings represent only a small portion of the deaths that are occurring," said Calambokidis, a member of a special Farallones vessel impacts advisory council. "The true number may be 10 or 20 times that."

Blue whales are far from the only victims. Ship strikes are believed to be a primary reason the critically endangered northern right whale has not recovered after being almost killed off by centuries of whaling. Only 20 or 30 right whales still exist on earth. The last one seen in California was about seven years ago in Monterey, according to naturalists with the Gulf of the Farallones National Marine Sanctuary.

More whales than ships were spotted during the recent expedition, which was put together by the marine sanctuary, Cascadia Research and the Oceanic Society. That's the way it should be, Calambokidis said.

"Contact with whales may hardly ever occur, but when you've got a lot of ships out there, hardly ever occurring could amount to a large number of whales," he said. "There are some fairly simple solutions. Most of the people I've talked to in the shipping industry want to be a part of the solution."

Blue whales

Distribution: There are now about 10,000 blue whales in all oceans of the world, a fraction of their historic numbers.

Size: They are the world's largest mammal, and the largest animal to ever inhabit the earth. A small child could crawl through the largest blood vessel of a blue whale. Newborn calves are about 23 feet long and weigh 5,000 to 6,000 pounds.

Communication: They make deep, rumbling sounds that can be felt and heard.

Life cycle: It is estimated that they live past 50 years. Although they may be found singly or in small groups, it is more common to see blue whales in pairs, with the female in front.